In Patent Literature 1, there is disclosed a balancer device for an internal combustion engine coupled to an oil pump. A torque from a crankshaft is input to one end side of a drive-side balancer shaft, and is transmitted to one end side of a driven-side balancer shaft via a balancer drive gear and a balancer driven gear. The torque input to the one end side of the driven-side balancer shaft is transmitted to an oil pump via a drive mechanism including two gears provided on the other end side.